She uttered a racial slur at a 13-year-old boy and, when ignored, assaulted the teenager in an unprovoked attack.
Lynn Chan, now 20, was sentenced to a week-long short detention order (SDO) yesterday after she pleaded guilty in August to hurting the boy.
She was also given a six-month Day Reporting Order (DRO) and has to perform 180 hours of community service.
Offenders given SDOs have to serve a brief stint behind bars of up to 14 days. They will not have criminal records after serving their sentences.
DROs are administered by the Singapore Prison Service. Offenders have to report to a day reporting centre for monitoring and counselling, and will also undergo rehabilitation programmes.
The boy was waiting for his mother near his school in Yishun at around 5.50pm on March 22 when Chan, who was standing in a flat on the second storey of a nearby block, uttered a racial slur at him.
The boy cannot be named due to his age and court papers did not mention why Chan had said such words to him.
Deputy Public Prosecutor Jason Chua said: "The victim turned and saw the accused on the second floor. The accused began shouting at the victim, asking if the victim wanted to fight. The victim ignored the accused."
Still unhappy, Chan left the flat, marched downstairs to confront the boy and hit the left side of his face with an empty plastic bottle.
She also slapped his face at least five times and bit his back in a scuffle that ensued.
The boy's teacher, who witnessed the attack, stepped in to help his student and Chan fled the scene.
The court heard that the incident was captured on the teacher's in-vehicle camera.
The teenager's mother arrived minutes later and she alerted the police at around 6.20pm.
The boy was taken to a clinic where he was found to have scratch marks on his face and bite marks on his right shoulder blade.
Yesterday, the court heard that Chan, who was unrepresented, tried to make restitution of $318 to the boy and handed over an apology letter. However, the boy's father rejected them.
Before handing out the sentence, District Judge Eddy Tham said he had noted that Chan had taken steps to show remorse.
The judge also noted that Chan had attacked a young victim with "no provocation whatsoever".
Chan will begin her sentence on Oct 17 after the judge granted her a deferment as she has to settle some personal matters.
For causing hurt, she could have been jailed for up to two years and fined up to $5,000.